Typically, components of a dispensing system, such as the dispensing guns, filters and nozzles, have part numbers related to the specific component size, flow rating, or other component characteristics. These part numbers may be stamped or otherwise indicated on the component. It has been known to color code nozzles for purposes of identifying orifice size and/or flow rate associated with the nozzle. For example, the assignee of the present invention has sold nozzles for purposes of applying adhesive to nonwoven materials in which the retaining nuts associated with the nozzles are of a specific single color designating a specific size of the dispensing orifice.
Especially when dispensing relatively viscous liquids, such as hot melt adhesive, orifice size designation is not sufficient to define the ultimate flow rate from the nozzle. In this regard, a so-called engagement dimension or length, which essentially refers to the dispensing orifice length, also significantly affects the flow rating of the nozzle. With regard to orifice diameter, the flow rate will generally increase exponentially with increasing orifice diameter and will decrease linearly with respect to an increasing engagement dimension. Various types of nozzles are available, including extrusion nozzles which simply extrude one or more beads of adhesive and so-called swirl nozzles which extrude a bead of adhesive which is then impacted by air emitted from the nozzle to create a swirled adhesive pattern. In each case, both the orifice diameter and the engagement dimension are necessary factors to consider when determining the appropriate nozzle for a given application under specific material, pressure and temperature conditions.
A significant problem in the industry with respect to the nozzles noted above relates to replacement of the nozzles with like nozzles during maintenance or repair. If the orifice diameter and the engagement dimension are unknown to the maintenance or repair personnel, then accurate records must be kept to ensure that nozzles having the same orifice diameter and engagement dimension are replaced on the dispensing apparatus. Both of these dimensions must be held constant after any maintenance to maintain the same flow rate. If the apparatus is repaired or maintained using nozzles having either incorrect orifice diameter or incorrect engagement length, this could significantly and adversely affect the application of the viscous liquid material. Oftentimes, nozzles may be covered with adhesive and a part number of the nozzle may not be easily identified by inspecting the nozzle during use. Therefore, the apparatus must be shut down and the nozzle must be removed and inspected before it is possible to determine the correct nozzle size. The necessity for this close inspection can require significantly increased down time for the dispenser. Particular problems also exist with filters used in such dispensing systems. For example, if a filter size is not properly matched with the orifice size of a nozzle, then the orifice of the nozzle itself may act as the filter and become clogged with particulate matter.
For reasons such as those outlined above, it would desirable to provide nozzles and other dispensing hardware having improved visual identification capabilities.